On Thu, 02 Nov 2006, Nils Anders Danielsson <nad at cs.chalmers.se> wrote:
> Do you consider on to be above or below the Fairbairn threshold, by
> the way? I think it is above the threshold since
> * we get rid of two lambdas,
> * we get rid of the duplication of p,
> * and, most importantly, it is easier at a glance to tell what the
> function does (assuming one knows about on).
And now Ulf is in the process of proving that flip on is a functor
from C to C^op for any CCC C, with flip on defined as follows:
flip_on_A(B) = (A^B)^B
flip_on_A(f) = curry (curry (eval ∘ id × f) ∘ eval ∘ id × f)
Ulf might follow up with a proof. :)
--
/NAD